Recently, a secondary battery, which can be charged and discharged, has been widely used as an energy source for wireless mobile devices. Also, the secondary battery has attracted considerable attention as a power source for electric vehicles (EV), hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (Plug-in HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles using fossil fuels.
Small-sized mobile devices use one or several battery cells for each device. On the other hand, middle or large-sized devices, such as vehicles, use a battery module having a plurality of battery cells electrically connected to one another because high power and large capacity are necessary for the middle or large-sized devices.
Preferably, the battery module is manufactured so as to have as small a size and weight as possible. For this reason, a prismatic battery or a pouch-shaped battery, which can be stacked with high integration and has a small weight to capacity ratio, is usually used as a battery cell of a middle or large-sized battery module. In particular, much interest is currently focused on the pouch-shaped battery, which uses an aluminum laminate sheet as a sheathing member, because the pouch-shaped battery is lightweight and the manufacturing costs of the pouch-shaped battery are low.
Meanwhile, a conventional battery cell is configured to have a structure in which battery cells are arranged in the lateral direction to constitute a battery cell stack, the battery cell stack is mounted in a lower case, and an upper case is coupled to the lower case. Consequently, it is possible to increase the size of the battery cell stack in the lateral direction. However, it is not possible to increase the height of the battery cell stack.
Also, the tooling direction in which the upper case is coupled to the lower case after the battery cell stack is mounted in the lower case is formed from top to bottom with the result that it is not possible to arrange battery modules in the longitudinal direction since it is difficult to approach the battery modules.
Consequently, there is a high necessity for battery module configured to have a structure in which battery cells are vertically stacked to constitute a battery module, the number of the battery cells is adjusted based on the installation height of the battery module, whereby it is possible to flexibly constitute the battery module, and the tooling direction in which the upper case is coupled to the lower case is changed so that battery modules can be arranged in the longitudinal direction.